In order to meet the demand for wireless data traffic, which has been increasing since the commercialization of a fourth-generation (4G) communication system, efforts are being made to develop an improved fifth-generation (5G) communication system or pre-5G communication system. For this reason, a 5G communication system or pre-5G communication system is referred to as a beyond 4G network communication system or a post Long Term Evolution (LTE) system.
To achieve a high data transmission rate, implementing a 5G communication system in an extremely high frequency (mmWave) band (for example, a 60 GHz band) is being considered. To relieve the path loss of signals and to increase the transmission distance of signals in an extremely high frequency band, beamforming, massive Multiple-Input and Multiple-Output (massive MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna techniques are under discussion for a 5G communication system.
Further, to improve the network of the system, technical development in an evolved small cell, an advanced small cell, a cloud Radio Access Network (cloud RAN), an ultra-dense network, Device to Device (D2D) communication, wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancelation is progressing for the 5G communication system.
In addition, an Advanced Coding Modulation (ACM) scheme including Hybrid Frequency Shift Keying and Quadrature Amplitude Modulation (FQAM) and Sliding Window Superposition Coding (SWSC) as well as an advanced access technique including Filter Bank Multi Carrier (FBMC), Non Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA) are being developed in the 5G system.
Among techniques for increasing the frequency efficiency and transmission rate of a wireless communication system, an MIMO transmission scheme is a method for transmitting a plurality of data streams at the same time using a plurality of transmitting/receiving antennas and has an advantage of increasing transmission rate in proportion to the number of antennas.
In order to resolve inter-symbol interference transmitted from a transmitting end of an MIMO wireless communication system, a receiving end may employ a linear equalizer using a linear scheme. As MIMO transmission/reception schemes, linear schemes including Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) methods and nonlinear schemes including a Maximum Likelihood (ML) method and sphere decoding have been proposed. Nonlinear schemes have excellent performance but involve high complexity (particularly, complexity sharply increases when the number of antennas increases). Linear schemes have relatively low complexity but are inferior in performance to nonlinear schemes.
An Integer Forcing (IF) MIMO scheme is newly proposed, which is similar in complexity to linear schemes but provides performance close to that of the ML method (as a nonlinear scheme) with optimal performance.
However, a method for applying the IF scheme to uplink (UL)/downlink (DL) Multi-User (MU) MIMO (MU-MIMO) communication has not yet been proposed.